The most likely reason is that you're using the wrong sign-in method. Split Pay accounts are tied to a specific sign-in method — Apple, Google, or email and password — that's set when you signed up. If you signed up with Apple or Google, an email-and-password attempt will fail every time, even if you set a password somewhere else.
Here's how to figure out the right method:
Check your email for the welcome message from Split Pay. It will indicate which method you used at signup.
Try to remember: Did you tap an "Apple" or "Google" button when you signed up, or did you create a password?
If you used Apple or Google, tap that button on the login screen — don't enter a password.
If you used email and password and don't remember the password, tap "Forgot Password" on the login screen to reset it.
While you're locked out, stop trying to log in — every failed attempt resets the 30-minute lockout timer. Wait the full 30 minutes from your last attempt before trying again with the correct method.
If you've verified your sign-in method and you're still getting locked out, contact support and we'll investigate.